1. Field of the Invention
The present invention relates generally to improvements in mounting the opposite ends of the transverse axle housings in a tandem axle suspension. The invention is shown and described as applied to a walking beam suspension, but could also be applied to other single- or multiple-axle suspensions.
2. Discussion
Tandem axle walking beam suspensions are well known in the art and are widely used, particularly on heavy duty trucks and truck tractors. Suspensions of the type to which the present invention relate are disclosed, for example, in Jabel and Taylor U.S. Pat. No. 4,699,399 dated Oct. 13, 1987. In such suspensions the opposite ends of the axle housings are mounted on the axle brackets which in turn are mounted on the adjacent ends of each pair of walking beams. One particular arrangement for mounting the end of an axle housing on an axle bracket which in turn is mounted on the adjacent end of a walking beam is shown and described in U.S. Pat. No. 4,699,399.
The present invention is directed to the means whereby the end of an axle housing is mounted on its associated axle bracket whereby the clamping forces applied to the axle housing are so balanced as not to appreciably distort or deform the normal shape of the housing. Heretofore, U-bolts have been used to clamp the ends of the axle housings to the axle brackets, or the brackets have been welded to the axle housings. Welded attachments have drawbacks, notably variations in weld quality and strength, and undesirable effects on materials of attaching parts due to heat of welding. These problems increase when the welding is performed in the field outside of a controlled factory environment. With previous clamped connections, the clamping forces and pressures exerted upon the axle housings are very great with the result that the relatively thin-walled axle housings yield or deform to a significant degree over periods of use. This yielding and distortion of the axle housing shape creates an objectionably frequent requirement to re-torque the attaching nuts on U-bolts in the field. Due to the sensitivity of a typical axle housing to the magnitude of the clamping force applied to it, proper detailed torque-up procedures for installation and maintenance should be carefully followed. If the compression clamping load exerted by the U-bolts is not properly applied within a safe range when a suspension is installed or during maintenance, the axle housing can become over stressed due to the dynamic loads introduced during operation, and seriously deformed. As a result, the clamped assembly can loosen if not timely re-torqued and can eventually come apart creating an undesirable condition. Accordingly, it is desirable to clamp the ends of the axle housings to the axle brackets in such a way that the housings are not appreciably deformed and the need for re-torquing is eliminated, or the frequency thereof at least greatly reduced.
Having regard for the foregoing considerations, the object of the invention, generally stated, is the provision of an improved way or system for clamping an end of an axle housing to an axle bracket mounted on the adjacent end of a walking beam in a tandem axle suspension so as to securely clamp the axle housing in place without welding, and without distorting or deforming forces being applied to the axle housing thereby eliminating damage to the axle housing, and eliminating, or substantially reducing the need for re-torquing.
Certain other, and certain more specific, objects of the invention will be apparent to those skilled in the art in view of the following description of three embodiments of the invention taken in connection with the accompanying drawings, wherein: